.flip-card-container {
	--hue: 150;
	--primary: hsl(var(--hue), 50%, 50%);
	--white-1: hsl(0, 0%, 90%);
	--white-2: hsl(0, 0%, 80%);
	--dark: hsl(var(--hue), 25%, 10%);
	--grey: hsl(0, 0%, 50%);

	/* width: 310px; */
	height: 120px;
	margin: 10px 0px;
	perspective: 1000px;
}

.flip-card {
	width: inherit;
	height: inherit;

	position: relative;
	transform-style: preserve-3d;
	transition: .6s .1s;
}

/* hover and focus-within states */
.flip-card-container:hover .flip-card,
.flip-card-container:focus-within .flip-card {
	transform: rotateY(180deg);
}

.message-front {
	width: 100%;
	height: 100%;
	padding: 5px 10px;
	border-radius: 10px;
	background: var(--white-1);
	opacity: 0.8;
	position: absolute;
	top: 0;
	left: 0;
	overflow: hidden;
	backface-visibility: hidden;
	box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.9);
}

.message-front .message-box {
	overflow: hidden;
	height: 80%;
	padding: 10px 5px;
}

.message-back {
	width: 100%;
	height: 100%;
	border-radius: 10px;
	background: var(--white-1);
	position: absolute;
	top: 0;
	left: 0;
	overflow: hidden;
	backface-visibility: hidden;
	display: flex;
	justify-content: center;
	align-items: center;
	opacity: 0.9;
}

/* .message-front */
.message-front {
	transform: rotateY(0deg);
	z-index: 2;
}

/* .message-back */
.message-back {
	transform: rotateY(180deg);
	z-index: 1;
}

/* figure */
figure {
	z-index: -1;
}

/* figure, .img-bg */
figure {
	position: absolute;
	top: 0;
	left: 0;

	width: 100%;
	height: 100%;
}

.message-back img {
	height: 100%;
	width: 100%;
	border-radius: 10px;
	image-rendering: -moz-crisp-edges;
	image-rendering: -o-crisp-edges;
	image-rendering: -webkit-optimize-contrast;
	image-rendering: crisp-edges;
	-ms-interpolation-mode: nearest-neighbor;
}

/* figcaption */
figcaption {
	display: block;

	width: auto;
	margin-top: 12%;
	padding: 8px 22px;

	font-weight: bold;
	line-height: 1.6;
	letter-spacing: 2px;
	word-spacing: 6px;
	text-align: right;

	position: absolute;
	top: 0;
	right: 12px;

	color: var(--white-1);
	background: hsla(var(--hue), 25%, 10%, .5);
}

/* button */
.message-back button {
	font-family: inherit;
	font-weight: bold;
	color: var(--white-1);

	letter-spacing: 2px;

	padding: 9px 20px;
	border: 1px solid var(--grey);
	border-radius: 1000px;
	background: transparent;
	transition: .3s;

	cursor: pointer;
}

.message-back button:hover,
.message-back button:focus {
	color: var(--primary);
	background: hsla(var(--hue), 25%, 10%, .2);
	border-color: currentColor;
}

.message-back button:active {
	transform: translate(2px);
}

/* 左上角钉子 */
.message-nail {
	position: absolute;
	left: 3px;
	top: -1px;
}

.message-nail i {
	color: #57606f;
	font-weight: bold;
}